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B::Xref - Generates cross reference reports for Perl programs
perl -MO=Xref[,OPTIONS] foo.pl
The B::Xref module is used to generate a cross reference listing of all definitions and
uses of variables, subroutines and formats in a Perl program. It is implemented as a backend
for the Perl compiler.
The report generated is in the following format:
File filename1
Subroutine subname1
Package package1
object1 line numbers
object2 line numbers
...
Package package2
...
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Each File section reports on a single file. Each Subroutine section reports
on a single subroutine apart from the special cases "(definitions)" and
"(main)". These report, respectively, on subroutine definitions found by the initial
symbol table walk and on the main part of the program or module external to all subroutines.
The report is then grouped by the Package of each variable, subroutine or format
with the special case "(lexicals)" meaning lexical variables. Each object
name (implicitly qualified by its containing Package) includes its type character(s) at
the beginning where possible. Lexical variables are easier to track and even included
dereferencing information where possible.
The line numbers are a comma separated list of line numbers (some preceded by
code letters) where that object is used in some way. Simple uses aren't preceded by a code
letter. Introductions (such as where a lexical is first defined with my) are
indicated with the letter "i". Subroutine and method calls are indicated by the
character "&". Subroutine definitions are indicated by "s" and format
definitions by "f".
Option words are separated by commas (not whitespace) and follow the usual conventions of
compiler backend options.
-oFILENAME
- Directs output to
FILENAME instead of standard output.
-r
- Raw output. Instead of producing a human-readable report, outputs a line in
machine-readable form for each definition/use of a variable/sub/format.
-d
- Don't output the "(definitions)" sections.
-D[tO]
- (Internal) debug options, probably only useful if
-r included. The t
option prints the object on the top of the stack as it's being tracked. The O
option prints each operator as it's being processed in the execution order of the program.
Non-lexical variables are quite difficult to track through a program. Sometimes the type of
a non-lexical variable's use is impossible to determine. Introductions of non-lexical
non-scalars don't seem to be reported properly.
Malcolm Beattie, mbeattie@sable.ox.ac.uk.
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